views: Make view::Views::GetPreferredSize() const.

ui/message_center/views/proportional_image_view.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_MESSAGE_CENTER_VIEWS_PROPORTIONAL_IMAGE_VIEW_H_
 #define UI_MESSAGE_CENTER_VIEWS_PROPORTIONAL_IMAGE_VIEW_H_
 
 #include "ui/gfx/image/image_skia.h"
 #include "ui/views/view.h"
 
 namespace message_center {
 
 // ProportionalImageViews center their images to preserve their proportion.
 class ProportionalImageView : public views::View {
  public:
   ProportionalImageView(const gfx::ImageSkia& image, const gfx::Size& max_size);
   virtual ~ProportionalImageView();
 
   // Overridden from views::View:
-  virtual gfx::Size GetPreferredSize() OVERRIDE;
-  virtual int GetHeightForWidth(int width) OVERRIDE;
+  virtual gfx::Size GetPreferredSize() const OVERRIDE;
+  virtual int GetHeightForWidth(int width) const OVERRIDE;
   virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
 
  private:
   gfx::Size GetImageDrawingSize();
 
   gfx::ImageSkia image_;
   gfx::Size max_size_;
 
   DISALLOW_COPY_AND_ASSIGN(ProportionalImageView);
 };
 
 }  // namespace message_center
 
 #endif // UI_MESSAGE_CENTER_VIEWS_PROPORTIONAL_IMAGE_VIEW_H_